On Saturday, October 5, 2019 at 8:02:14 AM UTC-4, wrote:

What is on the other side of the wall? Back in the olden days they
used to have a plywood access behind a tub. That practice may have
gone away by the late 70s tho.


What he said.

If you don't have an access panel, cut one in. If space allows, make it 14 x 14, then you can get prefab covers.

That said, I have that access panel and it didn't help my leak. I cut the ceiling downstairs so I could watch, and there were more problems than just one.

The drain footjoint leaked. That is a pain in the butt but I got it sealed.

The packing on the hot water faucet let a drip out when turned on. I couldn't get it apart, my plumber replaced the stems. Miracle, they still had parts for this one, unlike my other fixtures.

And then it started dripping only when the bath rather than shower was in use. Hard to diagnose, but my plumber caulked the overflow, we hope that fixed it. Not that water should ever go down there, but it seemed to be the problem.